Data from our previous study [37] were used as a basis for
the power calculation. The intervention should achieve a
medium interaction effect between the IG and the WLC
for the three measurement times: before treatment (T1), after
treatment (T2), and 3 months after the end of training of the
IG (T3). To statistically ensure this effect with a probability
of 80%, 14 participants should be included in each group
[3]. Because dropouts are to be expected, especially in a
study using a wait-list design, a dropout rate of 30% was
estimated. This means that a minimum of 36 children should
participate in the evaluation study.